Re: [PATCH 3/3] fm10k/igb/ixgbe: Use load_acquire on Rx descriptor

[Jeff Kirsher]

On Thu, 2014-11-13 at 11:27 -0800, Alexander Duyck wrote:
> This change makes it so that load_acquire is used when reading the Rx
> descriptor.  The advantage of load_acquire is that it allows for a
> much
> lower cost barrier on x86, ia64, powerpc, arm64, and s390
> architectures
> than a traditional memory barrier when dealing with reads that only
> have
> to synchronize to system memory.
> 
> In addition I have updated the code so that it just checks to see if
> any
> bits have been set instead of just the DD bit since the DD bit will
> always
> be set as a part of a descriptor write-back so we just need to check
> for a
> non-zero value being present at that memory location rather than just
> checking for any specific bit.  This allows the code itself to appear
> much
> cleaner and allows the compiler more room to optimize.
> 
> Cc: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
> Cc: Matthew Vick <matthew.vick@xxxxxxxxx>
> Cc: Don Skidmore <donald.c.skidmore@xxxxxxxxx>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/fm10k/fm10k_main.c |    8 +++-----
>  drivers/net/ethernet/intel/igb/igb_main.c     |    8 +++-----
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   11 ++++-------
>  3 files changed, 10 insertions(+), 17 deletions(-)

Based on the discussion on patch 01 of the series, it appears changes
are coming to the series, so I won't be picking up this patch.  I will
wait for Alex to re-spin the series with the suggested changes.

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